1. Field of the Invention
The present invention is related to stringed instruments, and more particularly, is directed towards bridge mechanisms utilized with stringed instruments.
2. Description of the Related Art
In order for a stringed instrument to be in tune, the octave point of each string must be aligned with its corresponding octave fret. The frets are located, for example, on the neck of an electric guitar or bass. The octave point of a string is defined by the overall resonant length of the string which is, in turn, defined by the distance between the contact point of the string at the nut and the contact point of the string at the bridge. The string does not vibrate acoustically beyond these two contact points. As long as the distance between the contact points at the nut and the bridge remains constant, the resonant length of the string, and therefore its octave point, also remains constant.
In modern electric guitars, for example, it is also recognized that the height of each string relative to the neck of the instrument is a matter of personal taste, and many mechanisms have been introduced to permit the height of individual strings to be varied. See, for example, U.S. Pat. No. 4,031,799 to Fender. This height adjustment is generally achieved by varying the spacing between the bridge and the body of the instrument by means of, for example, height adjustment screws that extend vertically through individual bridge sections, known as drums, over which the strings pass. Bridges conventionally may comprise a plurality of drums that are positioned in an end-to-end relationship; each typically having an upper groove, or saddle, to accommodate one string per drum. The contact point of a string at the bridge is where the string contacts its saddle.
However, it is also known that adjusting the height of a drum undesirably changes the length of its string, which, as stated above, changes the location of the string's octave point. It has therefore been recognized that in order to maintain the string in proper tune, it is necessary to simultaneously adjust the longitudinal position of the drum (and hence the contact point of the associated string) when height adjustments are made. A harmonic adjustment screw permits longitudinal movement of the drum (and saddle) to adjust string length and thus octave alignment. See, for example, U.S. Pat. Nos. 2,972,923; 3,290,980; and 3,427,916.
While the bridges described above do provide the necessary degree of individual adjustment for the strings, they result in certain disadvantageous effects. Specifically, because separate bridge components are present, rather than a unitary solid bridge, lateral vibration or movement of the drums results from string vibrations. The tone-sustaining capability of a given string is related to the inflexibility of the contact points at which the string is coupled to the instrument, that is, the nut and the saddle. If the drums vibrate at their string contact points, this vibration detrimentally reduces the tone-sustaining capability of the string. This drum vibrational movement further may cause the height and length adjustment screws to rotate within the drums as well, thereby altering the harmonic adjustment of the strings. This necessitates continuous and inconvenient readjustments.
One device to reduce drum vibration is disclosed in U.S. Pat. No. 4,031,799. The device consists of a bridge with a plurality of drums in which the strings also contact the harmonic adjustment screws coupling the drums to the base member of the bridge. Such an assembly was found to be inconvenient in practice by its inventor, according to his subsequent U.S. Pat. No. 4,281,576. Both of these patents also teach bringing the strings into engagement with the drums so as to force them into end-to-end contact, ultimately forcing the several drums against a fixed abutment on the bridge. See also U.S. Pat. No. 3,178,985. While all of these devices do reduce lateral drum vibration, they disadvantageously require the purchase and installation of an entire new bridge assembly. A further disadvantage is that the tension on all drums must be released prior to adjusting individual drums.
Vibrations of the height adjustment screws of conventional drums disadvantageously lowers them towards the bridge's base, thereby decreasing the height of strings above the neck.
No device is known that locks a stringed instrument's drums into a vibrationless mode, while simultaneously permitting the several drums to be independently adjusted.